Six leading UK insurance firms will plough £25bn into infrastructure projects in the country over five years, the Treasury said.

The private investment will help fund £375bn of projects under the Treasury's National Infrastructure Plan for the period to 2030.

These include energy, transport, flood defence, waste, water and communications infrastructure projects, to modernise and build on the country's creaking networks as the population grows.

Danny Alexander, chief secretary to the Treasury, said the insurance industry's investment is "a massive vote of confidence in the UK economy".

"This is great news for the people of the UK because after years of neglect, the UK's energy, road, rail, flood defence, communications and water infrastructure needs renewal," Alexander said.

"It will boost the UK economy creating jobs and making it easier to do business. It will also make the UK a better place to live for everyone who calls it their home."

The six insurers investing are Legal & General, Prudential, Aviva, Standard Life, Friends Life and Scottish Widows.

Otto Thoresen, director general of the Association of British Insurers (ABI), said the industry has "a key role to play in contributing to the UK's economic growth, as providers of long-term capital investment".

"Providing capital for infrastructure projects will help drive a competitive, healthy and resilient UK economy," he added.

Insurers look for long-term reliable investments that will deliver solid returns, allowing them to pay out on life insurance claims and pensions.

Labour said the announcement is still far short of what the UK needs in terms of infrastructure investment and there will be a real terms cut in capital investment in 2015/16.

"Scheme after scheme has been announced to great fanfare but then little actually delivered," said Chris Leslie, Labour's shadow financial secretary to the Treasury.

"Yet another announcement from Ministers about possible future investment will do little to reassure business that warm words will finally translate into diggers in the ground."

Among the work announced under the NIP is an extra £50m to develop the railway station at Gatwick Airport and a confirmed £1bn government guarantee for London Underground's Northern line extension to Battersea.